Recently, inductive materials have been used for accelerating pulp cells and differentiation of odontoblast cells for regenerating secondary dentin. Bone Morphogenic Protein (BMP) is one of these materials. Endochondral Bone Matrix Gelatin (Ec BMG) has been used less than others. This study was designed to evaluate dentin formation by Ec BMG in rabbit. Ec BMG was prepared"from tibia and femur of 4 Deutsche-Poland rabbits with average ages of 4-6 months. In this research, 12 rabbits were divided randomly to two groups (8 and 4 rabbits, respectively). In the first group, incisive tooth in one side was considered as experimental group and in other side as control group. In experimental group, pulp was exposed and Ec BMG was put in it. But, in control group, after exposing the pulp, tooth was dressed. In the second group, the rabbits were kept like the first group. They were killed in 28 and 60 days period time and their natural dentin was used for comparison of their calcium and phosphor with the first group. The light microscope and scanning electron microscopic study were performed on days of 28 and 60 after operation. Also, new secreted matrix was analyzed for measuring calcium and phosphor on all groups. The histological results on day 28 showed secondary' dentin and osteodentin formation in experimental group. The scanning electron microscopic observation on 60th days after operation in experimental group showed mineralized mass on site of Ec BMG implantation. In contrast, in control and second groups, no mineralized mass was observed. Analyzing of new secreted matrix in experimental group showed the high deposition of calcium and phosphate on Ec BMG implantation site. But, the amount of calcium and phosphate in experimental group was the same as the second group. Results of present investigation indicated that, implantation of Ec BMG in pulp cavity could induce pulp cells, secondary dentin and osteodentin in rabbit. So, Ec BMG can be effective in repairing of dentin related defects.